Waszczykowski was commenting on reports by German weekly Frankfurter Allgemeine Sonntagszeitung that the NATO summit could be transferred to one of the Baltic countries.

The paper said that international organisation could take such a step if Polish authorities do not stop “dismantling the rule of law”.

“Nonsense. There is no such threat. The Warsaw Summit must be held in Warsaw. Two years ago, a decision was made. Documents are printed, work schedules have been adopted,” Waszczykowski told reporters in Brussels on Sunday.

Meanwhile, former defence minister Tomasz Siemoniak, deputy head of the opposition Civic Platform (PO) party, told the Gazeta Wyborcza daily “speculation that the summit in Warsaw will not take place, or that US President Barack Obama will not take part, is unwarranted.”

The protests, which were organised by NGO the Committee for the Defence of Democracy (KOD) and opposition party Nowoczesna, were held under the slogan “let's bring back constitutional order”.

The demonstrations came hot on the heels of the government's confirmation on Saturday that it will not publish a key ruling by the Constitutional Tribunal, despite being urged to do so by Council of Europe watchdog the Venice Commission, which Poland's foreign minister had invited to Poland. (rg/pk)